Set GOMAXPROCS automatically

This is required in containerised environments to properly set
GOMAXPROCS to actual container limits set and not the whole underlying node's CPUs

See:
https://github.com/uber-go/automaxprocs

Author: amuraru

go.mod

@@ -42,6 +42,7 @@ require (
 	github.com/prometheus/client_model v0.3.0 // indirect
 	github.com/prometheus/common v0.37.0 // indirect
 	github.com/prometheus/procfs v0.8.0 // indirect
+	go.uber.org/automaxprocs v1.5.1 // indirect
 	go.uber.org/multierr v1.8.0 // indirect
 	golang.org/x/crypto v0.3.0 // indirect
 	golang.org/x/net v0.2.0 // indirect

go.sum

@@ -383,6 +383,8 @@ go.opencensus.io v0.22.4/go.mod h1:yxeiOL68Rb0Xd1ddK5vPZ/oVn4vY4Ynel7k9FzqtOIw=
 go.uber.org/atomic v1.7.0/go.mod h1:fEN4uk6kAWBTFdckzkM89CLk9XfWZrxpCo0nPH17wJc=
 go.uber.org/atomic v1.10.0 h1:9qC72Qh0+3MqyJbAn8YU5xVq1frD8bn3JtD2oXtafVQ=
 go.uber.org/atomic v1.10.0/go.mod h1:LUxbIzbOniOlMKjJjyPfpl4v+PKK2cNJn91OQbhoJI0=
+go.uber.org/automaxprocs v1.5.1 h1:e1YG66Lrk73dn4qhg8WFSvhF0JuFQF0ERIp4rpuV8Qk=
+go.uber.org/automaxprocs v1.5.1/go.mod h1:BF4eumQw0P9GtnuxxovUd06vwm1o18oMzFtK66vU6XU=
 go.uber.org/goleak v1.1.10/go.mod h1:8a7PlsEVH3e/a/GLqe5IIrQx6GzcnRmZEufDUTk4A7A=
 go.uber.org/goleak v1.1.11 h1:wy28qYRKZgnJTxGxvye5/wgWr1EKjmUDGYox5mGlRlI=
 go.uber.org/multierr v1.6.0/go.mod h1:cdWPpRnG4AhwMwsgIHip0KRBQjJy5kYEpYjJxpXp9iU=

main.go

@@ -17,6 +17,7 @@ import (
 	"github.com/cloudhut/kminion/v2/prometheus"
 	promclient "github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"go.uber.org/automaxprocs/maxprocs"
 	"go.uber.org/zap"
 )
 
@@ -43,14 +44,16 @@ func main() {
 	if err != nil {
 		startupLogger.Fatal("failed to parse config", zap.Error(err))
 	}
-
 	logger := logging.NewLogger(cfg.Logger, cfg.Exporter.Namespace).Named("main")
-	if err != nil {
-		startupLogger.Fatal("failed to create new logger", zap.Error(err))
-	}
-
 	logger.Info("started kminion", zap.String("version", version), zap.String("built_at", builtAt))
 
+	// set GOMAXPROCS automatically
+	l := func(format string, a ...interface{}) {
+		logger.Info(fmt.Sprintf(format, a...))
+	}
+	if _, err = maxprocs.Set(maxprocs.Logger(l)); err != nil {
+		logger.Fatal("failed to set GOMAXPROCS automatically", zap.Error(err))
+	}
 	// Setup context that stops when the application receives an interrupt signal
 	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt)
 	defer stop()